MPEG压缩域多尺度镜头切变检测算法

如何在压缩域进行镜头的切变检测一直是视频自动索引和检索中的难点。提出了一种MPEG压缩域多尺度镜头切变检测算法,在GOP、slot和B帧三个尺度上对MPEG视频流进行分析。通过对相邻I帧的检测,确定一个GOP中是否存在镜头切变;通过对slot的分析,确定镜头切变在GOP中所处的区域;通过对B帧的检测,确定镜头切变发生的确切位置。     

一种基于压缩域的实时跟踪改进算法

在基于压缩域的实时跟踪算法中,判别函数对目标外观考虑不足易造成跟踪精度较低。为此,提出一种改进的基于压缩域的实时跟踪算法。利用稀疏测量矩阵提取候选目标的低维多尺度特征,并根据在线更新的特征概率分布,采用朴素贝叶斯分类器判别目标与背景,实现粗跟踪。通过视频帧间候选目标内部区域所具有的相似性,在粗跟踪的基础上实施基于动态目标外观模型的二次跟踪,在线寻找目标的最佳跟踪位置。对多种跟踪视频库的测试结果表明,该算法在不过量增加计算负荷的情况下能有效提高跟踪精度。     

基于预处理的视频镜头边界检测算法

针对视频镜头边界检测的高时耗问题,提出了一种基于视频预处理的视频镜头边界检测(SBD)改进算法。通过使用自适应的阈值选择可能包含镜头边界的候选段,候选段内首帧与其余各帧进行相似度对比检测出镜头起始帧,并立即检测切变。若候选段中不包含切变,则进行渐变检测。调整候选段以保证镜头边界位于同一段内,段内其余各帧与起始帧进行相似度对比确定镜头结束帧。实验结果表明,所提算法镜头边界识别准确率能够达到90%以上,且与倒三角模式匹配方法相比能够节约时间15.6%~30.2%;与对渐变和切变分别检测的算法相比,该算法能够在满足识别率的基础上提升检测速度。     

基于HEVC压缩域的镜头边界检测方法

镜头边界检测是智能视频检索的一个重要环节。现有的检测方法主要是在像素域进行处理,切变检测精度不高,计算复杂度过大。针对这些问题,文中利用解析HEVC码流得到的编码信息,提出了一种基于HEVC压缩域的镜头边界检测方法。首先统计每帧编码信息中各类预测模式的PU个数,并根据CU深度对运动矢量进行幅值滤波;然后采用PU预测模式、运动矢量和帧比特数对切变候选帧进行两级筛选,再对其进行自适应阈值的镜头切变检测;接着根据切变帧对视频序列进行分段,并在时域上对帧比特数进行平滑滤波;最后使用PU预测模式和经滤波平滑后的帧比特数对分段视频进行镜头渐变检测。实验结果表明,该方法具有良好的镜头边界检测效果,并具有较低的计算复杂度。     

视频镜头时域分割方法的研究

视频时域分割指将视频序列分成若干镜头，是视频内容分析以及基于内容的视频浏览和检索的第一步．该文首先对视频结构以及视频镜头种类进行了简要的描述，然后对为计算不连续性而采用的提取特征和建立测量准则的常用方法进行概述．其后，文章介绍了检测镜头切变和渐变的算法及其优缺点．在压缩域上检测镜头变换边界的问题也在文中予以分析．在结论与展望中，提出了一些这一领域的难点和对今后工作的展望．     

压缩域视频内容分析与摘要提取技术

给出了压缩域视频摘要系统的结构框架,并对其中的压缩域视频镜头变换检测、关键帧提取和压缩域人脸检测等主要算法进行了讨论.     

时域多分辨率的非压缩域视频分割算法

由于非压缩视频序列具有明显的直观性视觉特征,并在实际应用中仍占据相当大的比重,针对在非压缩视频的处理中仍然存在对镜头变化的类型、镜头渐变和突变的位置分析不够准确的难点,提出了一种时域分辨率的非压缩域视频分割算法,在提取序列的基于强边缘块的直方图,比较不同序列之间的差异的基础上,采用多分辨率的算法进行镜头检测。实验证明,这种方法实现了自动视频分割并较好地克服了上述的缺点。     

时域多分辨率的非压缩域视频分割算法*

由于非压缩视频序列具有明显的直观性视觉特征,并在实际应用中仍占据相当大的比重,针对在非压缩视频的处理中仍然存在对镜头变化的类型、镜头渐变和突变的位置分析不够准确的难点,提出了一种时域分辨率的非压缩域视频分割算法,在提取序列的基于强边缘块的直方图,比较不同序列之间的差异的基础上,采用多分辨率的算法进行镜头检测。实验证明,这种方法实现了自动视频分割并较好地克服了上述的缺点。     

基于运动特征及位置估计的行人检测算法

根据行人运动的特点和行人在图像中位置与身高的对应关系,提出了一种结合运动特征与位置估计的行人检测算法。提取运动特征和聚合通道特征（ACF）,将提取的特征放到Real Adaboost分类器里进行训练,并对行人可能存在的位置建立评估模型;在检测阶段,通过分类器确定行人的候选区域,然后采用非极大值抑制算法去除重叠窗口,最后对行人候选区域应用位置评估模型进一步判断,以此排除可能的非行人目标。实验采用Caltech数据集对算法进行仿真,该算法的平均对数漏检率为27.12%,与ACF算法的相比降低了5.9个百分点。实验表明运动特征在视频检测中能够与静态特征进行信息互补,同时行人的位置估计在摄像机固定的情况下,具有一定的判断能力。     

基于压缩域的自适应场景叠化检测算法

给出了一种压缩域中快速有效的自适应场景叠化检测算法,该算法综合利用了视频帧中宏块类型信息的场景叠化和非场景叠化特征,并利用中值滤波对形成的数据流进行滤波,再利用滑动窗口准确地检测出场景叠化的开始帧和结束帧.实验结果达到了较高的查全率、查准率和F度量,并和现存的场景叠化算法进行了对比实验.     

一种基于模型的扫换检测方法

视频自动分割是实现视频数据库检索必不可少的一个过程,其基础是镜头边界检测.当前已有的算法能够较准确地检测出镜头突变,但对于镜头的渐变则常常会漏检,这是由于镜头渐变时帧间差没有一个明显的峰值,因而其检测比突变检测要困难得多.扫换是一种常用的视频空间编辑手段,用于实现多种镜头变化.通过分析各种类型的扫换,提出了一种新的基于视频空间编辑模型的扫换检测算法,其性能优于Alattar提出的基于统计特征的算法.对用AdobePremiere5.1生成的各种扫换视频进行检测.实验结果表明,这种扫换检测算法能够较好地适应     

基于DC系数和运动矢量的快速场景分割算法

场景分割技术是动态视频分析和基于内容的视频检索的基础，以检测出来的场景作为基本单元，可以进一步对视频内容进行分析和建立索引．本文旨在提出一种基于MPEG压缩视频流的场景分割算法，利用MPEG数据流中已有的DCT DC系数和运动矢量，来检测场景的变换，从而实现场景分割，针对实际视频流中场景突变和渐变两类变换．本文提出两种方法分别处理不同情况，对于突变检测，该算法可以定位到帧，由于该算法进行最小程度的解码，降低了计算复杂度，因而大大提高了检测速度．     

Statistical sequential analysis for real-time video scene change detection on compressed multimedia bitstream

The increased availability and usage of multimedia information have created a critical need for efficient multimedia processing algorithms. These algorithms must offer capabilities related to browsing, indexing, and retrieval of relevant data. A crucial step in multimedia processing is that of reliable video segmentation into visually coherent video shots through scene change detection. Video segmentation enables subsequent processing operations on video shots, such as video indexing, semantic representation, or tracking of selected video information. Since video sequences generally contain both abrupt and gradual scene changes, video segmentation algorithms must be able to detect a large variety of changes. While existing algorithms perform relatively well for detecting abrupt transitions (video cuts), reliable detection of gradual changes is much more difficult. A novel one-pass, real-time approach to video scene change detection based on statistical sequential analysis and operating on a compressed multimedia bitstream is proposed. Our approach models video sequences as stochastic processes, with scene changes being reflected by changes in the characteristics (parameters) of the process. Statistical sequential analysis is used to provide an unified framework for the detection of both abrupt and gradual scene changes.     

Sudden scene change detection in compressed video using interpolated macroblocks in B-frames

This paper addresses an important area in video processing, namely compressed domain processing. For video indexing, video scene transition detection is an essential step to segment the video. Current techniques for scene change detection tend to suffer from a major limitation as most of them cannot identify scene transitions in the compressed domain. Since most video is expected to be stored in the compressed domain, scene transition detection in this domain is highly desirable. In this paper an algorithm for video scene change detection is proposed to overcome this limitation. In this scheme, properties of the B-frames are used as it is capable of measuring the correlation between two adjacent reference frames. The results show that this scheme performs better than schemes based on P-frames. Proposed scheme can be directly applied with compressed data with minimum decompression and hence it is computationally efficient and makes real time implementations possible. Results show that video scene transitions can be identified satisfactorily with the proposed scheme.     

基于内容的视频检索的突变场景变换探测算法

讲述了目前正在使用的突变场景变换探测算法，并列举了一种新的基于压缩视频的突变场景变换探测算法，实验结果显示，这个算法不受视频种类的限制，能取得满意的结果。     

基于多种视频特征的镜头边界检测算法

提出一种基于多种视频特征的自适应镜头边界检测算法.利用滑动窗口将当前帧与其前后相邻多帧的视频特征进行比较,形成2组相似向量,利用Fisher判别式与运动矢量形成的自适应阈值实现突变检测.提取帧的亮度方差作为特征,通过有限状态机实现渐变检测.对大量TRECVID视频进行实验,结果表明该算法对突变和渐变都具有良好的检测性能,对运动及闪光具有较好的鲁棒性.     

Enhanced Eigen-Audioframes for Audiovisual Scene Change Detection

In this paper, a novel audio-visual scene change detection algorithm is presented and evaluated experimentally. An enhanced set of eigen-audioframes is created that is related to an audio signal subspace, where audio background changes are easily discovered. An analysis is presented that justifies why this subspace favors scene change detection. Additionally, a novel process is developed in order to detect audio scene change candidates in this subspace. Visual information is used to align audio scene change indications with neighboring video shot changes and, accordingly, to reduce the false alarm rate of the audio-only scene change detection. Moreover, video fade effects are identified and used independently in order to track scene changes. The false alarm rate is reduced further by extracting acoustic features in order to verify that the scene change indications are valid. The detection methodology was tested on newscast videos provided by the TRECVID2003 video test set. The experimental results demonstrate that the proposed method achieves an F-measure exceeding 0.85. Accordingly, it effectively tackles the scene change detection problem     

场景切换视频自适应帧间码率控制

针对视频帧中可能出现的大量场景切换,提出一种基于非连接点的场景切换检测算法,提高编码性能,该场景检测算法复杂度低,在运动估计的同时,完成视频场景切换检测。场景切换将导致GOP(group of pictures)长度的变化,并可能出现GOP长度太短的情况。提出改进的自适应GOP时域滤波技术,避免由于GOP太短引起的编码性能下降。针对视频场景切换检测分割出的不同长度的GOP,提出一种基于率失真模型的帧间码率控制算法,利用视频的失真与码率及视频帧复杂度的关系,对帧间码率分配进行优化,提高重构视频帧的总质量。实验结果表明,基于场景检测的自适应帧间码率控制算法能够获得较好的编码性能。     

基于宏块类型信息的自适应场景变换检测算法

提出了一种压缩域中利用B帧的宏块类型信息自适应场景变换检测算法，采取滑窗方式自适应地检测场景突变和场景渐变的准确位置。利用电影、动画、新闻等素材作为实验视频库，并利用MPEG 2作为实验平台，取得了较高的查全率和查准率。     

A shot detection technique using linear regression of shot transition pattern

Video segmentation acts as the fundamental step for various applications like, archiving, content based retrieval, copy detection and summarization of video data. Shot detection is first level of segmentation. In this work, a shot detection methodology is presented that evolves around a simple shot transition model based on the similarity of the frames with respect to a reference frame. Frames in an individual shot are very similar in terms of their visual content. Whenever a shot transition occurs a change in similarity values appears. For an abrupt transition, the rate of change is very high, while for gradual it is not so apparent. To overcome the effect of noise in similarity values, line is fit over a small window using a linear regression. Thus slope of this line exhibits the underlying pattern of transition. A novel algorithm for shot detection, hence, is developed based on the variation pattern of the similarity values of the frames with respect to a reference frame. First an algorithm is proposed, which is direct descendant of the underlying transition model and applies a threshold on the similarity values to detect the transitions. Then this algorithm is improved by utilizing the slope of linear approximation of variation in similarity values rather than the absolute values, following least square regression. Threshold on the slope is determined with a bias towards minimizing false rejection rate at the cost of false acceptance rate. Finally, a simple post-processing technique is adopted to reduce the false detection. Experiment is done with the video sequences taken from TRECVID 2001 database, action type movie video, recorded sports and news video. Comparison with few other systems indicates that the performance of the proposed scheme is quite satisfactory.